For many years sump pumps have been employed in low locations, e.g. basements of homes and business buildings, to protect against undesired accumulations of water such as may occur as a result of heavy rains, sewer blockages, etc. It is not uncommon for these sump pumps to fail either by reason of electrical power failure, such as often occurs as a result of a bad storm, or by reason of a functional failure in the pump or its motor. To guard against such malfunctions supplemental, battery operated, pumps are employed in the sump to take over when the primary pump fails. One such apparatus is described in my prior U.S. Pat. No. 3,634,842. It is extremely important that the supplemental pump operate properly when it is called upon to do so.
It is not uncommon for there to be floating debris in the sump. Such debris may include solid debris such as paper, sticks, leaves and the like. Also, it will often include various scum forming materials such as oil, grease, soap, detergent, chemicals, etc. While these scum forming materials will generally pass through the pump, while it is operating, without causing any obstruction, over a period of time the scums that they form can dry and build up on components impairing operation. Of course, the paper, sticks, etc., are likely to impair the action of the pump should they enter the pump while it is operating and therefore it is important to prevent them from reaching the intake opening of the pump. This obviously can be done by screening and a screen with relatively large openings can be employed which will not impair the flow of liquid to the intake opening of the pump. However, the scum forming materials will pass through such a screen, particularly if it has relatively large openings, with the scum then building up on the inside of the screen and the components within the screen. When this occurs, there is a danger of impairment of the operation of the pump. It is not possible to screen out the scum forming materials, at least without seriously restricting the flow of liquid to the pump and, perhaps, not then. This can be a particularly serious problem with a secondary or back-up pump which operates only very infrequently; yet, the necessity for such a pump to operate when required is all the more important.
The principal object of the present invention is to provide an apparatus for protecting the intake of such an emergency sump pump by screening out the solid floating debris and at the same time restricting the entry of the floating scum forming materials to the interior of the screen. Through the use of the present invention, the screen openings can be relatively large, being dictated solely by the size of the solid floating debris.
In a further feature of the invention, the floating scum forming materials are denied entry to the interior of the screen, both during the normal operation of the primary sump pump and also during the normal operation of the emergency sump pump. At all times, however, the liquid to be pumped can flow to the interior of the screen and the solid debris is filtered out.
Further objects and advantages will become apparent from the following description.